Spray desiccation apparatus



Patented Aug. 15, 1922.

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H. J. ZIMMERMANN SPRAY DESICCATION APPARATU3.

APPLICATlON FILED OCT. 2.5;1918- Patented Aug. 15, 1922.

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H. J. ZIMMERMANN SPRAY DESICCATION APPARATUS.

APPLICATION FILED 00125, 1918.

Patented Aug. 15, 1922.

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H. J. ZIMMERIVIANN SPRAY DESICCATION APPARATUS.

APPLICATION FILED 00125. 1918 Patent ed Aug. 15, 1922.

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HANS J. ZIMMERMANN, or cnrcaco, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO B. s'rurzxn COMPANY. a CORPORATION or rumors.

SPRAY DESICCATION APPARATUS.

Specification of Letters Patent. Patented Aug. 15, 1922.

Application filed October 25, 1918. Serial 'No. 259,655.

To all whom it may concern:

Be it known that .I, 'HANS J. ZIMME'R- MANN, a citizen of Germany, residin at Chica o, in the county of Cook and tate of Ilhnois, have invented a new and useful Spray Desiccation Apparatus, of which the following is a specification.

The present invention relates to improvements in apparatus for carrying on the process'of spray desiccation and will be fully understood from the following specification, taken in connection with the accompanymg drawings, in which Fig. 1 is a longitudinal vertical section through a superheated vapor desiccation apparatus; Fig. 2 is a transverse section through the circulating fan thereof; and Figures 3, 4L and 5 are, respectively, longitudinal sections through various modified forms of the apparatus.

Referring first to the construction shown in Figures 1 and 2, there is illustrated a vertical cylindrical drying chamber, designated 10, having a frusto conical shield 11 at the upper end, which terminates short of the upper'head of the chamber to leave an annular inlet 12. The spray nozzles, of which three are diagrammatically illustrated, project downward through the upper head, terminating in spray orifices at the approximate level of the shield 11.

The lower end of the cylindrical chamber 10 forms a conical hopper 13, which is reduced in diameter to such an extent that it may form a central inlet for a centrifugal circulatin fan let, the shaft 15 of which is co-axial with the cylinder 10. The housing of the fan 14 is of the usual spiral or volute form, as shown in Fig. 2, and communicates with a duct 17 preferably rectangular in cross-section and having a curved axis which represents in effect a continuation of the spiral curvature of the casing 16 of the fan. Theduct 17 forms the tangential inlet of a cyclone collector 18 which is vertically disposed in close proximity to the fan. The outlet for the collected solids from the cyclone collector 18 is located at the baseof the latter, as shown at 19.

The vapor or gas outlet'from the collector is represented at 20, being in the usual location, that is, co-axial with the collector and dependin a consideradle distance into the latter. he cyclone outlet conduit 20 is shown as provided with'two vertically disposed baffles 21, pointed on the bottom and arranged at right angles to one another, as

is common practice in. this art. At 22 there IS shown the connection of a vapor outlet pipe which serves to release vapors from the system to maintain a constant pressure therein, as will subsequentl appear. Above this pipe the conduit 20- 1s flared as at 23 to connect with a tubular superheater, the vertical tubes of which are fastened in horizontal tube sheets 24. The space Sue-1, rounding the heating tubes is supplied with.

a heating fluid; for example, steam under I pressure, by a pipe 25, the condensate being withdrawn at the base through the pipe 26. Above the upper tube sheet 24 there in ar ranged an upwardly inclined duct 27, which communicates with the annular chamber around the shield 11 and thence with the annular inlet 12 of the dryin chamber.

The entire apparatus described with the exception of the shaft 15 of the blower or circulating fan and the upper head of the drying chamber, is enclosed by a heat insulating housing 28, which may be formed of any suitable insulation material, such as cork or magnesia.

The apparatus above described operates according to the method disclosed in the patent to Richard W. G. Stutzke, No. 1,215, 889, issued Feb. 13, 1917. In brief, thev liqluid to be treated is introduced under consi erable pressure through the. spray nozzles at the top of the drying chamber and there mingles in finely divided form with the decending current of the superheated vapor of the liquid menstruum. For example, in the case of an aqueous sugar solution the finely divided droplets will be enveloped in a descending current of superheated steam. As this current moves toward the bottonof the drying chamber the liquid content of the droplet will be evaporated and the resultant fine solid particles will travel along in suspension in the descending steam current. In-the base of the drying chamber this cur rent will be contracted in cross-section and simultaneously accelerated in velocity as it enters the central axial inlet of the fan 14. By the action of the latter the direction of the current will be changed at right angles to its former course and simultaneously a very considerable centrifugal-force will be brought into lay as the current of steam and suspended solids traverses the fan and of this centrifugal action there will be effected within the fan itself a marked separation between the solidsand the steam current, these solids closely hugging the wall of the casing 16. As the mixed stream asses out of the fan the centrifugal action is maintained by the curved conduit 17, the

' separated solids following the outer wall of this curved passage until they are dischar ed into the cyclone collector l8. Wit in this collector the work of separation is "of the drying chamber,the whole of the circompleted, the efliciency of the separation being very much higher than in the case of an ordinary cyclone collector of the same size and design, owing to the fact that the fan itself and the delivery conduit from the fan to the cyclone is of such form as to ac- "compllsh an initial separation which is maintained up to the time of admission of the stream to the cyclone.

The separated solid constituents of the liquid under treatment are released from the bottom of the cyclone while the steam passes out of the central inlet 20 thereof and thence to the superheater. A mass of steam corresponding to that introduced in the form of water by the nozzles 12 will be continuously vented through theoutlet 22 so that the pressure within the system will remain constant. In its passage through the tubes of the superheater the circulating steam current will again be brought to its initial temperature, and guided by them-- clined conduit-27, will be introduced with a minimum of resistance into the upper end of the drying chamber 10.

It is to be particularly noted with respect to the arrangement of the apparatus above described thatthe various elements thereof, i. e., the drying chamber, fan, collector and superheater, are disposed in such relative positions as to operate most advantageously. Thus, since the drying chamber is vertical, there is no tendency for the liquid which is introduced to be deposited on the walls thereof nor for the solids resulting from the treating of the liquid to be so deposited. On the contrary, the action of gravity on the liquids and dried solids merely serves to keep them in suspension in the descending steam current and to carry them to the inlet of the fan, it being notedthatthis inlet is centrally arranged and coaxial with respect to the drying cylinder. Change of direction of the flow which is inherent in the cen trifugal blower or fan illustrated is made to serve the purpose of directing the circulate ing current horizontally, as is required for its tangential entry into a vertically disposed cyclone collector. It is to be further noted that the separating effect of the fan is maintained by the curved conduit 17. The cyclone collector, being like the centrifugal fan an instrument which inherently changes the direction of flow, it therefore becomes possible by the arrangement" described to employ a straight extensionof t cyclone outlet 20 as the upwardly leadi g return conduit, for the circulating current. The tubular superheater described constitutes a part of this return conduit and performs its functions without changing the direw of flow.

It will therefore be noted that with the exception of the inclined duct 27 connecting the space above the superheater with the top culatingsystem described may becalled a natural circulation, that is, there are no elbows or right-angle conduits employed for the purpose of connecting the various essential elements of the system, these elementsthemselves beinginstead so relatedthat they form in effect a circulatory system. Not only does this arrangement reduce to an absolute minimum. the power required for maintaining circulation through the system, prevent deposition of solids at any point save in the collector and increase the efliciency of the latter, but there is secured another highly important result, which is that of 24 An outlet flue 32 on the opposite sideof the superheater and near the lower tubesheet thereof is connected with a jacket chamber 33 which surrounds the drying chamber 10. A chimney 34:, which lies parallel with the drying chamber, has upper and lower flues 35, 36, each in communication with the acket chamber 33. A damper 37 arranged in the chimney between these two flues may be used to control the heating of the acket 33. Thus with the damper in the closed position the combustion gases from the Dutch oven 30, after traversing thev superheater, must pass through the entire length of the jacket 33 before they may escape into the chimney through the upper. flue 35. On theother hand, if the damper 37 be opened, a direct passage for the combustion gases is afforded around the bottom of the drying chamber 10 and by the flue 36 to the base of the chimney.

In the construction of Fig. 3 I have illustrated the circulating fan and cyclone collector as being separately lagged or insulated instead of being included within a common insulation housing.

In Fig. 4 I have illustrated a further modification of the invention which is particularly designed for use with a-desiccation system not employing the superheated vapors of the liquidlas a drying medium. This system is identical in arrangement with that of Figure 1, save that a heat-exchange apparatus is inserted between the cyclone collector and the heater proper. This heatexchange apparatus co'm rises a barrelshaped housing'4O which orms a continuation of the cyclone outlet 20 and having therein a pair of horizontal annular tube sheets 41 connected by three concentric rows of tubes 42. The lower tube-sheet 41 is of less diameter than the housing 40, while the upper tube-sheet is of the same diameter as the upper end of the housing. A conical" deflector 43 is secured to the lower tube-sheet 41 and another deflector 44 of greater conicity to the upper tube-sheet. The cooling coil 45 occupies the space between the deflector 44 and the tubes 42, being provided with pipe connections for the circulation of a cooling fluid. The lower cone 43 serves as a catch-basin for liquid condensate and has a drain-pipe 46 tapped into its lower end to carry off such condensate. The drain outlet may be protected by a conical deflector 47 having drainage holes near its periphery, as illustrated.

Above the heat-exchange apparatus described in the foregoing there is mounted a heater, which may be of the same construction as the superheater described in connection with Figure 1.

The operation of the apparatus illustrated in Fig. 4 is as follows. Assuming that an indifferent gas, such as air, occupies the circulatory system, and that liquid to be deslccated is introduced into the drying chamber as described, such air will become partially cooled and laden with the vapors of the liquid before it escapes from the drying chamber. The dried solids having been precipitated out in the cyclone collector, this more or less cooled or saturated air current enters the heat-exchange apparatus, passes between the three concentric rows of tubes 42, being there partially cooled, and is deflected by the cone'44 over the pipe-coil 45, where it is further cooled and a portion of the vapors which it carries are condensed out. This liquid condensate is caught by the basin formed by the lower deflector 43 and continuously withdrawn through the drain 46. After passing through or over the pipe-coil 45 the air current enters the lower ends of the tubes 42 and in traversing the latter is partially re-heated by exchange of heat with the entering air. It then passes to the superheater, enters the drying chamber and completes. its cycle in the manner above described.

In Fig. 5 I have illustrated another modified form of the apparatus arranged for use in an ordinary manner without resorting to circulation of the drying medium. This aparatus is identical with that described in ig. 1 save that the outlet 20 of the collector is connected to an elbow 50 and thence to any suitable discharge conduit leading away from the apparatus. Similarly, another elbow 51 serves to connect an inlet conduit with the base of the heater. In the construction shown in Fig. 5, therefore, atmospheric air or other gas is admitted to the apparatus, as shown, passes through the heater, where its temperature is raised and its capacityfor absorbing or carrying off liquid vapors increased, is then introduced into the drying chamber, passes through the latter and through the fan and cyclone collector, and is discharged from the system.

While I have in the foregoing described in considerable detail several specific embodiments of my invention, it will be understood that this is illustrative only and for the pur-' pose of making the invention more clear and that the invention is not limited to these details nor to any of them except in so far as such limitations form a part of the accompanying claims, in which it is my intention to claim all novelty inherent in the invention as broadly as is permissible in view of the prior art.

What I regard as new and desire to secure by Letters Patent is:

1. In combination with a vertical drying chamber, a centrifugal fan mounted below the said chamber and with its axis vertical, the central axial inlet of the fan forming the bottom of the said chamber, a vertical cyclone dust collector mounted in proximity to the said fan, and a communication duct forming the tangential outlet of the said fan ing chamber, a centrifgual fan at the base of the said chamber, the central axial inlet of the fan forming the bottom of the chamber, a vertical cyclone collector in close proximity to the fan, a horizontal duct connecting the fan and cyclone collector and forming a tangential outlet for the former and a tangential inlet for the latter, a vertical duct connected with the cyclone collector outlet at the lower end and with the upper end of the drying chamber, and means for heating the circulating medium located within the said duct.

3. A circulatory spray desiccation apparatus comprising a vertically disposed drying chamber, a centrifugal fan at the base of the said chamber, the central axial inlet of the fan forming the bottom of the chamber, a vertical cyclone collector in close proximity to the fan, a horizontal duct connecting the fan and cyclone collector and forming a tangential outlet for the former and a tangential inlet for the latter,'and a vertical duct connected with the cyclone col- 5 lector outlet at the-lower end and with t e pper end of the drying chamber.

4. The combination with avertically dis- .posedoyclone dust collector, of a centrifugal and a horizontal duct forming the tangential outlet of the fan and the tangential inlet of'the said collector, the axis of said ,dilct having a curvature in the same direction as that of the fan casing, whereby the initial separation obtained within the fan is maintained through the duct and into the cyclone HANS J. ZIMMERMANN. 

